It is known to provide electrostatic screens in coil winding, the screen serving the dual purpose of insulating one winding from another and also providing an electrostatic screen to prevent unwanted spurious transfer from one winding to another in a transformer. Whilst the winding of the wire to form a coil has been a rapid process the interleaving of one winding with another by an electrostatic insulating screen has often introduced considerable delays into the process of coil winding particularly where the insulating material and metal foil has had to be interleaved by hand.
It is obviously imperative that the metal foil is fully insulated from both windings and also from itself so that an electrical short circuit does not occur and further delays have been experienced in the past while insulation tests have been carried out prior to continuing winding.
It is an object of the present invention to provide apparatus for pre-forming an insulating electrostatic screen which can be wound directly around a coil during manufacture and which will have reliable insulating properties.
It is another object to provide an improved composite tape.